Cranking time limiter for internal combustion engines



Nov. 17, 1942. L L. HALL 2,302,315

CRANKING TIME LIMITER FOR INTERNAL COMBUSTION ENGINES Filed May 31, 1941 v INVENTOR ALI/www.- Lm 1:. Haw

/M Q BY Patented Nov. 17, 1942 GRANKING TIME LIIVHTER FOR INTERNAL COMBUSTION ENGINES Luther L. Hall, Horsehcads, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application May 31, 1941, Serial No. 396,104 6'Claims. (c1. zed-3s) The present invention relates to a cranking "*furcated elastic blade I9 connected to the lead time limiter for internal combustion engines and """il, anchored at one end as indicated at 2| and more particularly to voltage compensating decarrying a contact 22 on its free end which is vices therefor. normally in engagement with a fixed contact 20 Cranking time limiters in order to be comconnected to the lead I2. Means for opening mercially acceptable must maintain the crankthe contacts after a predetermined time battery voltages.

ing time limit reasonably constant in spite of wide variations in ambient temperatures and to utilize some form of compound thermostat to compensate for variations in ambient temperature, and to employ a current limiting device such as a ballast tube to counteract the eflect of voltage variations. However, the incorporation of these devices includes some complication in construction and added expense, particularly in connection with the ballast tube.

It is an object 01' the present invention to provide a cranking time limiter for engine starters It is now commercial practice 1} end through a compression spring 26 to the tree of cranking is provided in the form of a bimetallic arm 24 mounted at one end on an adjustable bracket -25 and connected at its free end of the contact blade IS. The bi-metallic arm 24 is arranged to bend downwardly when heated, thus causing the spring 26 to push the contact,22 out of engagement with contact 20 and into engagement with contact 23 connected to any suitable form or alarm device A, means for heating the arm during the cranking operation is provided in the form of a heating coil 21 which is arranged to be energized during closure which is compensated for variations in ambient 0f the Starting circuit A h re own, is is temperature and battery voltage.

It is another object to provide such a device which isreliable in operation and simple and parent from the following description taken in connection with the accompanying drawing in which the figure illustrates semi-diagrammatically an engine starting system incorporating a preferred form of the invention, the parts being shown in the positions assumed when the cranking operation has been interrupted by the cranking time limiter.

1n the drawing there is illustrated a starting system including a battery grounded at 2 and connected by a lead 3 to a magnetic starting switch 4. Switch 4 is connected by a lead 5 to the starting motor S. M. which is grounded at I to complete the starting circuit.

A control circuit for the magnetic switch 4 is provided including the battery I, lead 1, manual switch I, and lead 9, which is connected to a cranking time limiter device indicated generally by numeral II. The cranking time limiter, is connected by a lead l2 to a circuit controlling device It which is connected by a lead M to the coil ii oi the magnetic switch 4. Coil II is grounded through lead It and normally closed contacts II, II to complete the control circuit.

accomplished by means of a heating circuit comprising a lead 28 connected to the starting motor lead 5 and through a current regulating device indicated generally by 29 to the heating coil by means oi a lead 3|, the coil 21 being grounded in order to complete the heating circult.

According to the present invention the current regulating device 29 is arranged to place a var- 30 iable resistance in the heating circuit in accordance both with the ambient temperature obtaining and with the voltage of the battery I. As' here shown this is accomplished by means of a resistance element 32 which is connected at 35 one end to the heating circuit lead ii, and a contact 33 mounted on the end of a thermostatic'arm .34 in position to bear on the resistance 32 and to move along said resistor as the arm 34 flexes in response to temperature changes.

40 Thermostatic arm 34 is provided with a heating during the cranking operation. Arm 34 is so arranged that a rise in temperature theerot causes the contact 33 carried thereby to move along the resistor 32 in a direction to include more of the resistor in the heating circuit for coil 21 and thus reduce the eiIect thereof on the thermostatic arm 24.

In the operation of the starting system closure of the manual switch 8 completes the control circuit for the magnetic switch 4 through lead 8,

The cranking time limiter ll comprises a bicontacts 20, 22, lead l2,-circuit controller II,

lead ll, coil [5, lead i8, contacts l1, l8 to the ground. Switch 4 is accordingly caused to close and complete the starting circuit through leads 3 and 5 thus energizing the starting motor. Closure of the starting circuit causes energization of the heating circuit for both the heating coils 35 and 31 so that both the thermostatic arms 24 and 34 are heated during the cranking operation.

It the engine fails to start after a pre-determined time of cranking, the thermostatic arm 19 bends downward sufficiently to bring the compression spring 26 beyond its dead center position whereby it will cause the blade I! to move up, opening contacts 20, 22, and closing contacts 22, 23 as illustrated. The starter control circuit is thus broken, interrupting the cranking operation, and the alarm is actuated. The time of cranking is regulated by the amount or resistance introduced into the heating circuit by the resistor". This amount is controlled by the position of the contact a: which is determined by the temperature of the thermostatic arm 34. Since the initial temperature of the arm 34 is i the same as the ambient temperature, the initial resistance in the heating circuit for the arm 24 depends upon the ambient temperature. the rise in temperature of the arm 34 is directly dependent on the. voltage across the heating coil 35, and the coil 35 is directly connected to the battery, it the battery voltage is high, the arm' 34 will be quickly heated and the resistance of the resistor 32 will be rapidly increased, thus reducing the heating effect of the coil 21 on the arm 24. On the other hand, if the battery voltage is low, the heating effect of the coil 35 is reduced, and less resistance is interposed in the heating circuit for the coil 21.

It will thus be seen that the current regulating device 29 compensates for both ambient temperature and voltage variations so as to render the heating effect of the coil 21 substantially constant irrespective of variations in these two conditions.

Although but one embodiment of the invention has been shown, and described in detail, it will be understood that other embodiments are possible, and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

Since What is claimed is:

l. A cranking time limiter for engine starters including a thermostat, heating means for the thermostat, and means controlling the heating means, operative to increase the heating effect responsive to a decrease in ambient temperature and to maintain the heating eflect substantially constant irrespective of variations in voltage of the power source.

2. A cranking time limiter for engine starters including a thermostat, heating means tor the thermostat, a rheostat for controlling the heating means, and means tor increasing the resistance of the rheostat responsive to a rise in ambient temperature.

3. A cranking time limiter for engine starters including a thermostat, heating means for the thermostat, a rheostat for controlling the heating means, unitary means responsive to a rise in voltage of the power source and to a rise in ambient temperature for increasing the resistance 0! the rheostat.

4. In a cranking time limiter for engine starters a starter control circuit including a set of contacts, a thermostat for opening the contacts, a heater for said thermostat, an energizing circuit therefor in parallel with the starting motor including a rheostat, a second thermostat for varying the resistance of the rheostat and a heater coil for the second thermostat also connected in parallel with the starting motor.

5. In an engine starter, control means for interruting the cranking operation including a thermostat, means for heating the thermostat during the cranking operation, a variable resistor for controlling th heating means, and means for adjusting the resistor to compensate for variations in voltage of the source 0! cranking energy.

6. In an engine starter, control means for interrupting the cranking operation including a thermostat, means for heating the thermostat during the cranking operation, a variable resistor, for controlling the heating means, heatsensitive means for adjusting the resistor to increase its-resistance responsive to a rise in temperature, and a heater for the heat sensitive means energized from the source of cranking energy.

LUTHER L. HALL. 

